Crystal amplifier



Apnil129, 1952 E. T. CASELLINI CRYSTAL AMPLIFIER Filed July 23, 1948 IN VEN TOR.

W I Y-M ATTORNEY Patented Apr. 29, 1952 CRYSTAL AMPLIFIER Ezio T. Casellini, Salem, Mass., assignor to Sylvania Electric Products Inc., Salem, Mass., a corporation of Massachusetts Application July 23, 1948, Serial No. 40,259

9 Claims.

This invention relates to semi-conductors such as crystals and the like.

Such semi-conductors have been used with two contacts for rectification and oscillation, but my invention is directed toward making them useful also for amplification and other purposes by adding an additional electrode. The additional electrode may be in the form of a mesh grid on the crystal surface, with one or more of the usual catwhisker electrodes passing through the openings in the grid to contact the crystal. The grid may be made to function as a contact electrode and may have a positive direct current line voltage, with the catwhisker as the output electrode being, for example, negative, or the functions and polarities of the electrodes may be reversed, the positive and negative voltages being taken with respect to the usual back electrode on the crystal.

Other features, objects and advantages of the invention will be apparent from the following specification, taken with the accompanying drawing in which:

Figure 1 is a sectional view through the crystal, and

Figure 2 is a view taken at the contact surface of the crystal.

In the figures, the crystal I, which may for example, be of germanium containing a small amount of activating impurity such as tin, has the usual back contact 2 which may be a metal piece soldered thereto, and will generally be of larger area than the other contacts, namely the grid 3 and catwhiskers, or pointed Wires 4, which rest on the surface of crystal I under the proper tension for good sensitivity. Except for the addition of the grid 3, the unit may be made, for example as shown in my copending application Serial No. 492,163, filed June 23, 1943, all catwhiskers 4 being connected together, for example.

The mesh of the grid should be such that the distance between its wire 5 is quite small, preferably no more than a few thousandths of an inch, for effective results. A lead-in wire 6 may be attached to grid 3, and the mechanical tension between the grid 3 and crystal I adjusted by means of this wire 6 or in some other convenient manner.

The grid 3 may be of evaporated metal condensed directly on said crystal surface if desired, or placed on said surface by some other form of metallic deposition.

A single catwhisker 4 may, of course, be used, but the use of a number of these intermeshed 2 with, but spaced from the grid wires, converts the device into the equivalent of a power tube.

This application is related to copending application Serial No. 39,367, filed July 1'7, 1948, by Orrlck H. Biggs, now abandoned, and to application Serial No. 39,529, filed July 19, 1948, by Harold Heins, this application as well as those referred to above being assigned to a common assignee.

What I claim is:

1. A semi-conductor unit comprising a semiconducting crystal, a metallic mesh grid on the surface thereof and catwhisker contacts to said crystal and passing severally through apertures in said grid close to but out of direct contact with said grid.

2. A semi-conductor unit comprising a semiconductor crystal, a grid of closely spaced wires on the surface thereof and a point contact to said crystal passing between and close to, but spaced from said wires.

3. A semi-conductor unit comprising a semiconductor crystal, a number of catwhiskers contacts thereto, and a wire grid on said crystal surface and intermeshed with, but spaced from, said catwhisker contacts.

4. A semi-conductor unit comprising a semiconducting crystal, a metallic member in surface contact with said crystal and having numerous apertures, multiple point-contacts severally penetrating said apertures out of contact with said member, and an additional large contact engaging said crystal.

5. A semi-conductor unit comprising a semiconducting crystal, a back contact on said crystal, a wire mesh grid on the surface of said crystal, and plural point-contacts engaging said crystal through the apertures of said wire grid and insulated from said grid.

6. A semi-conductor unit comprising a body of semi-conductor, a metallic member in face contact with said body and having numerous apertures, and a plurality of point-contact elements engaging said body and passing through said apertures out of direct contact with said metallic member.

'7. A semi-conductor unit comprising a body of semi-conductor, a generally flat apertured wiremesh member in surface contact with said crystal, a point-contact element engaging said body and extending through an aperture in said member close to but out of contact therewith, and an additional large contact engaging said body.

8. An electrical translator including a body of semi-conductive germanium, a generally fiat multi-apertured contact engaging the surface of said body of limited extent perpendicularly away from said surface, an additional large contact engaging said crystal, and plural point-contact elements penetrating the apertures in said contact member and extending substantially perpendicularly from said surface, the apertures in said multi-apertured member being sufficiently small so that said apertured member engages said body close to said point-contact elements, but being out of contact with said elements.

9. An electrical translator including a body of semi-conductor, a plurality of point-contact elements engaging said body at mutually spaced REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,524,033 Bardeen Oct. 3, 1950 

